1. Field of the Invention
The present invention relates to the mobile communication technologies, particularly to a data transmission method, data reception method and corresponding apparatuses, with which radio resource consumption in the wireless communication systems can be reduced.
2. Description of Prior Art
In the Third Generation (3G) communication systems and the evolution of the 3G communication systems, the interface between an eNode B (also called a base station) and an UE (User Equipment) is usually called the “Uu” interface, via which data related with users is transmitted and received.
Each side of the eNode B and the UE is usually divided into a Packet Data Convergence Protocol (PDCP) layer, a radio link control (RLC) layer, a medium access control (MAC) layer and a physical layer. The PDCP layer, RLC layer and MAC layer are served as the second layer (L2 layer) in the Open Systems Interconnection (OSI) solutions, and the physical layer is served as the first layer (L1 layer) in the OSI solutions.
Data transmitted in the PDCP layer is called “PDCP PDU”, which includes a serial number SN and a “PDCP SDU (PDCP Service Data Unit)”. Data transmitted in the RLC layer is called “RLC PDU”, which includes a RLC header and a “Data Part”. Data transmitted in the MAC layer is called “MAC PDU”, which includes a “MAC header” and a “MAC SDU”.
In usual, each PDCP PDU has a PDCP serial number (PDCP SN). Such a serial number is necessary for the reception side, since it can guarantee that the PDCP at the reception side work normally, for example, the PDCP layer at the UE works correctly. FIG. 1 shows a mapping relationship between PDCP PDU and RLC SDU. In such a scenario, each PDCP PDU includes a PDCP SN and a PDCP SDU is mapped to one RLC SDU. Consecutive RLC SDUs have continuous PDCP SNs. A series of RLC SDUs are mapped to one RLC PDU sequentially. That is, a series of PDCP PDUs each comprising a PDCP SN and a PDCP SDU are mapped to one RLC PDU.
As shown in FIG. 1, for example, a PDCP PDU usually includes a necessary serial number such as SN_1 and a necessary data part such as PDCP SDU 1, which will be mapped into the RLC layer as a part of data units transmitted in that layer.
In such a scenario, taking the transmission side as an example, an operating procedure on the user plane is shown in FIG. 2. As shown in FIG. 2, a plurality of PDCP PDUs are mapped to a data part of one RLC data packet, for example, PDCP PDU_1 to PDCP PDU_n in Logical Channel_1 are mapped as RLC PDUs of the RLC layer data packets. In other words, each RLC PDU includes a RLC header and a RLC PDU data part formed by a plurality of PDCP PDUs.
As shown in FIG. 2, a plurality of RLC PDUs are mapped into the MAC layer as MAC SDUs of a MAC PDU, and further transmitted in the physical layer.
Therefore, one RLC PDU includes many continuous PDCP SNs in case PDCP PDUs are consecutive. However, due to the continuity of the PDCP PDUs, if a PDCP SN of a first RLC SDU is known, PDCP SNs of the subsequent RLC SDUs can be estimated automatically. In other words, there is redundancy in the mapping procedure from the PDCP layer to the RLC layer, which leads to radio resource waste.